Apparatus and method for conducting thermolysis of plastic waste in continuous manner

ABSTRACT

The subject of the invention is apparatus and method for thermolysis of waste plastics especially polyolefins where reaction feedstock, reaction residuals and reaction products are removed continuously. Apparatus for thermolysis of waste plastics especially polyolefins includes plastic feeding system, pyrolysis reactor, discharge system according to the invention characterized in that after the plastic feeding system ( 1 ) the extruder ( 2 ) and pyrolysis reactor ( 3 ) which height is at least 1.5 time bigger than its diameter are situated. Pyrolysis reactor is equipped with dual high speed propeller ( 7 ). Method for thermolysis of plastic waste especially polyolefins thermolysis in the presence of inert gas according to the claim characterized in that plastic waste are continuously fed to the extruder where plasticized at 180° C. to the temperature of the reactor later are fed to the pyrolysis reactor where at 350° C.-450° C. at mixers&#39; 30-1500 rpm the thermolysis is carried out with continuous two step fractional condensation where light product boiling below 180° C. goes to storage tank with cold jacket and heavy product boiling above 180° C. goes to hot jacket tank.

This invention provides a method for apparatus for conducting thermolysis of the plastic waste and a method of thermolysis with continuous waste plastics especially polyolefin feeding and continuous discharging carbonizable substances and reaction leftovers.

U.S. Pat. No. 6,534,689 description defines method of pyrolysis of the waste plastics led to fuel production. To separate solid particles from liquids the cyclone using high vehicle velocity and high inert gas temperature as heat transfer carrier. Invention utilizes inert gas and hydrocarbon vapours as heating medium.

Patent P-380619 description the method and apparatus for catalytic depolymerization of polyolefinic waste plastics characterized by two reactors in which depolymerization takes place, one tank reactor and second flow reactor operating in cooperation. Shredded plastic waste are first heated, melted and pumped under the reaction medium surface. Later plastic molten mass is dispersed in the reaction medium. Depolymerization process occurs in presence of the catalyst. From reactor bottom reacting mixture is pumped to the flow reactor in which it is heat up to 400° C. Reaction occurs under normal and negative pressure. Pressure in the reactor depends on the planned outcome product properties. Inside flow reactor depolymerization takes place. Gas and liquid mixture comes in to tank reactor where it is split into gas and liquid fraction.

Liquid phase is heated up and melts incoming plastic feedstock. In the bottom reactor area in 360° C. the initial reaction takes place. In upper section in around 400° C. the split in to gas and liquids takes place. Hydrocarbon vapours produced comes thru the active chemically neutralizing filter and condensed. Process is continuous.

From Patent P-383709 description it is known the apparatus ad method for depolymerization of polyolefinic waste plastics especially polyolefins with removing reaction leftovers and residues. Apparatus consist of feeding conveyor, pyrolysis reactor, discharging section characterized by gas engaging stabilizer equipped with mixer and working in close loop at least one external pyrolysis reactor with screw or ribbon mixer and pipe that closes the loop. Depolymerization process is carried in inert gas presence and characterized by reactor with reactor with enforced dual flow in which in which on direction is used as well to discharge the reactor's residue.

Principal aim of the invention is thermolysis method of the waste plastics especially polyolefins carried out continuously with continuous feeding and discharging the apparatus at the same time with minimizing coke formation and carbonizable products. Apparatus to conduct waste plastic pyrolysis consists of feeding system, main pyrolysis reactor and discharging system according to the invention characterized in that after the feeding system there is an extruder followed by thermolysis reactor which height is 1.5 time bigger than its diameter and equipped with dual mixer.

Favourably thermolysis reactor has at least two vertical wall baffles.

Favourably thermolysis reactor's height is two times bigger that its diameter.

Favourably thermolysis reactor is equipped with independent accessory mixer.

Favourably mixer is high speed mixer with different propeller blade angles.

Favourably mixer is a double turbine mixer.

Favourably mixer is equipped with additional stabilizing bars.

Favourably discharge system constitute discharge valve.

Favourably discharge system constitute discharge system.

Favourably discharge system is equipped in upper discharge valve, discharge chamber, bottom discharge valve and discharge tank placed on the scale.

Favourably upper discharge valve and bottom discharge valve are equipped with drain mechanisms.

Favourably drain mechanism is sealed hand drain bar.

Favourably thermolysis apparatus has at least one thermo separation column for product condensation.

Favourably upper section of the thermo condensing column is heated.

Favourably thermo separation column in connected to two separate storage tanks, one for light second for heavy fraction.

Favourably light fraction storage tank has cold water jacket and heavy fraction tank has not water jacket.

Operating mode of the waste plastic thermolysis at presence of inert gas according to the invention characterize in that waste plastics are fed continuously to the extruder and plasticized at the temperature from 180° C. up to the reactor temperature and plasticized polymer is fed to the thermolysis reactor where at 350-450° C. at mixer 30-1500 rpm thermolysis of carried out where reaction residues are discharged continuously and thermo separation column continuously condense and divide two streams of fractions one below 180° C. and second above 180° C.

Favourably thermolysis is carried out at 390 to 450° C.

Favourably thermolysis is carried out at 200 to 700 rpm of the mixer.

Favourably plastic wastes are extruded at 250 to 370° C.

Favourably upper section of the thermo separation column during operating thermolysis reactor is heated up causing self condensation of one of the fractions.

Favourably light fraction is received in cold water jacket tank at 20° C. and heavy fraction is collected in hot water jacket tank at 70 to 80° C.

Basic advantages of the invention are small size process equipment enable to carry out thermolysis continuously and giving repeatable end products at lower temperature of the process without using catalysts.

Process of thermolysis became very stable in favour to little temperature difference between molten plastic and working temperature of the thermolysis reactor. It affects the overall energy consumption and lowers feedstock residence time in the reactor. Implementing the reactor with vertical baffles enables proper mixing.

More over implementing high speed dual mixers enabled more efficient mixing, radial and axial temperature distribution.

Right/left mixer rotation enables discharging the reactor in both mixer's rotating directions.

Additional advantage comes from thermoseparation column presence and its heated/non heated upper condensing section. Thermo separation column operates non heated mode by heating to certain temperature by the vapours coming from the thermolysis reactor and regulating the volume of the vapours coming up and down the column.

Additional advantage of the system is equipping the reactor in residue discharge system consisted of high temperature resistant discharge valves.

Products of descried system are solvents represented as light fraction and oils and waxes represented by heavy fraction for further processing.

Invented system is described on the FIG. 1-scheme of the system for thermolysis of the waste plastic or plastics especially polyolefin's.

EXAMPLE

Apparatus for conducting thermolysis of plastic waste according to the invention is characterized by granulated feedstock feeding system (1) to the extruder (2). Plasticized polymers at 300 to 330° C. is fed to the thermolysis reactor (3) where depolymerization process takes place. Reactors (3) height is two times bigger that its diameter. Reactor (3) is equipped in dual high speed propeller (7) with different propeller blade angle. Reactors (3) is equipped in three vertical baffles (8). Thermolysis process is carried out at 390 to 415° C. at mixer speed 200 to 700 rpm. Residuals from thermolysis process are continuously discharged in (4) system (5). Discharge system (5) is equipped in upper discharge valve (9), discharge chamber (10), lower discharge valve (11) and discharge tank (12) placed on the scale (13). Upper discharge valve (9) and lower discharge valve (11) have draining mechanisms respectively (9′) and (11′). Drain mechanism (9′) and (11′) is manual. Apparatus includes thermo separation column (6) for fractional condensation. Upper section of the column (6) is optionally heated.

Column (6) is connected with two receiving tanks dedicated to light (15) and heavy (16) fractions. Storage tank (15) has cold water jacket (17) and storage tank (16) has hot water jacket (18).

In thermo separation column (6) continuous two stage condensation is carried out with light fraction condensation at temp. less than 180° C. (<180) and heavy fraction condensation at temp. higher than 180° C. (>180). Light fraction is received in cold jacket tank at temp. 20° C. and heavy tank received in hot jacket tank (18) at temp. 70 to 80° C. Thermolysis is carried out at presence of inert gas-nitrogen. Heavy fraction can be further processed into greases, petroleum jelly and waxes. 

1-15. (canceled)
 16. Apparatus for thermolysis of waste plastics especially polyolefins comprising plastic feeding system, pyrolysis reactor, discharging system characterized by plastic feeding system (1) followed by extruder (2) and pyrolysis reactor (3) which height is at least 1.5 times bigger than its diameter and which is equipped with dual propeller (7).
 17. The apparatus according to claim 16 wherein the pyrolysis reactor (3) is characterized by at least one of: a. comprising at least two vertical baffles (8); b. a height two times bigger than its diameter; and c. comprising an independent auxiliary mixer.
 18. The apparatus according to claim 17 characterized in that the dual propeller (7) is a high speed mixer with different mixers blade angle.
 19. The apparatus according to claim 18 characterized in that mixer is a high speed propeller (7).
 20. The apparatus according to claim 17 characterized in that the high speed propeller (7) is equipped with auxiliary claws.
 21. The apparatus according to claim 16 characterized in that the apparatus further comprises discharge section (4) wherein the discharge section (4) is a discharge valve or a discharge system (5) and wherein the discharge system (5) is equipped with an upper discharge valve (9), a discharge chamber (10), a lower discharge valve (11) and a residual tank (12) placed on a scale (13).
 22. The apparatus according to claim 21 characterized in that each of the upper discharge valve (9) and lower discharge valve (11) are individually equipped with cleaning mechanisms respectively (9′) and (11′) and wherein the cleaning mechanisms (9′ and 11′) are optionally manual pipe cleaners.
 23. The apparatus according to claim 16 characterized in that it has at least one thermo separation column (6) to condense and separate products wherein the upper section of the thermo separation column (6) is optionally heated.
 24. The apparatus according to claim 23 characterized in that the thermo separation column (6) is connected with two independent storage tanks (15 and 16) for light fraction (15) and heavy fraction (16).
 25. The apparatus according to claim 24 characterized in that storage tank (15) is equipped with cold water jacket (17) and storage tank (16) is equipped with hot water tank (18).
 26. A method for thermolysis of waste plastics especially polyolefins in presence of inert gas characterized in that plastic wastes are fed from feeding system to the extruder and plasticizes at 180 degrees centigrade to reactor's temperature where molten plastic is fed to thermolysis reactor where in 350 degrees centigrade to 450 degrees centigrade and at mixers' 30-1500 rpm the thermolysis is carried out where residue is discharged continuously and in thermo separation column a two step fraction condensation to the storage tanks designated for light fraction boiling to 180 degrees centigrade and heavy fraction boiling above 180 degrees centigrade.
 27. The method according to claim 26 characterized in that thermolysis is carried out at temperature 390-415 degrees centigrade and/or at mixers' 200-700 rpm.
 28. The method according to claim 26 characterized in that plastic wastes are plasticized in extruder at 250 to 370 degrees centigrade.
 29. The method according to claim 26 characterized in that thermo separation column upper section during reactor operation is heated causing partial self condensation of the product.
 30. The method according to claim 26 characterized in that light fraction is received in cold jacket storage tank and heavy fraction is received storage tank with 70 to 80 degrees centigrade hot jacket. 